An essential part of any cooking process (e.g., frying or baking) is transport of moisture away from the food product at the same time that heat is being transferred into that food product. Transporting moisture out of the food is a critical factor governing texture (e.g. crispness), color (e.g. effect on browning reactions), internal starch structure (e.g. degree of gelatinization), and flavor generation during cooking. For example, frying foods such as french fries in oil blends with low moisture transport properties can lead to a non-crisp, limp textured cooked product which is considered unappealing to the consumer. Therefore, superior frying mediums have an optimum moisture transport rate that produces foods with good texture and taste.
Conventional cooking oils made from edible fats are known to produce fried foods which have desirable texture and flavor. These edible fats may comprise saturated and/or unsaturated triglycerides, as well as monoglycerides, diglycerides, or other emulsifiers. Although foods fried in these fats have desirable texture and taste, their ingestion at high levels is known to significantly contribute to obesity and health risks such as coronary heart disease. Therefore, a need exists for cooking oils which do not add calories and fats to the foods cooked in them.
Cooking oils comprising polyol fatty acid polyesters have been developed in order to reduce fat and calories of foods cooked in oils. For example, U.S. Pat. No. 3,600,186, Mattson et al., issued Aug. 17, 1971, discloses low calorie food compositions produced by replacing at least a portion of the fat content of a conventional food with a sugar fatty acid ester or sugar alcohol fatty acid ester. These esters have at least 4 fatty acid ester groups, with each fatty acid having from 8 to 22 carbon atoms. These sugar or sugar alcohol fatty acid esters which contain unsaturated fatty acid ester groups and/or a preponderance of short chain, i.e. less than C.sub.14, fatty acid ester groups are generally liquid at room temperature. A plastic shortening is disclosed made with 50% sucrose octastearate. A deep fat frying oil is disclosed made from the erythritol tetraester of olive oil fatty acids (ETOFA). These compositions are found to reduce the fat and the calorie levels of the foods cooked in them. Pan frying and deep fat frying of various foods in ETOFA, such as potato pieces, eggs, beefsteaks, breaded shrimp and breaded codfish steaks, are disclosed therein.
U.S. Pat. No. 4,797,300 of Jandacek et al., issued Jan. 10, 1989, discloses a shortening composition comprising from about 75% to about 90% of an edible oil having a complete melting point below 37.degree. C. and from about 10% to about 25% of a solid polyester of sucrose wherein the ester groups consist essentially of a mixture of short chain saturated fatty acid radicals containing from C.sub.2 to C.sub.10 and long chain saturated fatty acid radicals containing from C.sub.20 to C.sub.24, in a molar ratio of short chain to long chain fatty acid radicals of from about 3:5 to about 5:3, and wherein the degree of esterification is from about 7 to about 8. The shortening is said to be useful in frying oils, and for cooking a variety of foods having reduced fat and calories. Example 1 discloses a sucrose polyester containing four caprylic acids and four behenic acids per sucrose molecule.
U.S. Pat. No. 4,005,195 of Jandacek, issued Jan. 25, 1977, discloses liquid polyol fatty acid polyesters and anti-anal leakage agents used for the treatment of hypercholesterolemia. In Example IV, a cooking fat is disclosed made with 50% liquid sucrose polyester and 50% cocoa butter. The sucrose polyester comprises about half the heptaester and about half the octaester (or an average 7.5 ester) of sucrose and oleic acid.
U.S. Pat. No. 4,005,196 of Jandacek et al., issued Jan. 25, 1977, discloses a combination of liquid polyol polyesters, anti-anal leakage agents, and fat-soluble vitamins. Example VI discloses a cooking fat made with 70% sucrose octaoleate and 30% sucrose octastearate.
U.S. Pat. No. 4,034,083 of Mattson, issued Jul. 5, 1977, discloses polyol fatty acid polyesters fortified with fat-soluble vitamins and used in food or pharmaceutical compositions for treating and/or preventing hypercholesterolemia. Cooking oils and plastic shortenings are specifically mentioned. In Example V, Mattson discloses a plastic shortening, containing 40% xylitol pentaoleate, which is suitable for use in frying and other types of cooking. Ingestion of foods cooked in said oil can reduce the body's serum cholesterol level.
European Patent Application 0,236,288 of Bernhardt, published Sep. 9, 1987, discloses sucrose polyesters esterified with C.sub.8 to C.sub.22 fatty acids. The preferred fatty acid composition is said to be 9-12% palmitic, 42-53% stearic, 19-39% oleic, 2-17% linoleic, 0-2% linolenic, 0-2% arachidic, 0-10% behenic, and 0-2% erucic. The polyesters are disclosed as being useful in making frying oils, and foods fried in oils such as potato chips, corn chips, and other fried farinaceous snack foods.
Jandacek et al., Physical Properties of Pure Octaesters, 22 Chemistry and Physics of Lipids, 163-176 (1978), discloses sucrose octaesters of the following fatty acids: caprylic, capric, lauric, myristic, palmitic, stearic, oleic, elaidic and linoleic. Polymorphism, heat of fusion, melting of binary systems, refractive index, viscosity, density, and interfacial tension of sucrose octaesters is disclosed. Particular uses for the sucrose octaesters, however, are not disclosed.
Kester et al., Food Technology 40 (12), pp. 47-59, December 1986, generally discusses edible coatings which retard moisture and gas transmission into and out of foods. Lipids, due to their relative low polarity, are said to block moisture transmission when applied in a thin layer to the surface of food products such as crackers. It is stated that paraffin and beeswax are greatly resistant to water transmission because of their molecular compositions; paraffin wax consists of a mixture of long-chain, saturated hydrocarbons, while beeswax comprises 71% hydrophobic, long-chain ester compounds, 15% long-chain hydrocarbons, and 8% long-chain fatty acids. Kester states that the effectiveness of a particular surfactant film in reducing moisture evaporation was influenced by the structure of the surfactant; the 16- and 18-carbon fatty alcohols, as well as glycerol monopalmitate and glycerol monostearate, were most effective. FIG. 2 shows a correlation between hydrocarbon chain length and inhibition of water evaporation for a single layer of monoglyceride and fatty alcohol surfactants; the lower the chain length (down to C.sub.10), the less that evaporation was inhibited. U.S. Pat. No. 4,960,600, Kester et al.,issued Oct. 2, 1990, discloses the use of polyol fatty acid esters for reducing the rate of moisture transmission into and out of foods. The polyol fatty acid esters have at least 4 fatty acid ester groups, wherein at least 90% of the fatty acids contain not less than 16 carbon atoms. Said compositions are used as thin coatings for foods such as cereals and starch-based snack foods.
A problem associated with use of liquid nondigestible oils, i.e., those having a melting point below body temperature (about 37.degree. C.), is an undesired "passive oil loss effect", (hereinafter oil loss) which is manifested in leakage of the nondigested liquid oil through the gastrointestinal tract's anal sphincter. Regular ingestion of moderate to high levels of completely liquid forms of these polyol polyesters can produce this oil loss. Suitable oil loss control agents include higher melting fatty materials i.e. triglyceride hardstocks, solid sucrose polyesters, and mixtures thereof. These agents are disclosed in U.S. Pat. No. 4,005,195, Jandacek, issued Jan. 25, 1977; U.S. Pat. No. 4,797,300 to Jandacek et al, issued Jan. 10, 1989; and U.S. applications Ser. Nos. 514,800 to Young et al; 514,793, 514,794, and 514,903, all to Letton et al., and filed Apr. 26, 1990; all herein incorporated by reference.
It is therefore a further objective of this invention to provide reduced calorie cooking oils which have superior cooking properties, good oxidative stability, and passive oil loss control.
All parts, percentages and ratios used herein are by weight unless otherwise indicated.